Acclimation for heat resistance in Trichogramma nr. brassicae: Can it occur without costs?

Abstract

1. It is well known that animals can increase their stress resistance by prior exposure to sub-lethal conditions, but this acclimation process is often accompanied by deleterious fitness effects. These may reflect a cost of acclimation, or more general costs arising from damage due to sub-lethal exposures. 2. Acclimation for increased adult resistance to a 40 °C heat shock was tested in the egg parasitoid, Trichogramma nr. brassicae, following exposure of immature stages to 33 °C for different periods. Prepupal exposure did not increase heat resistance, but daily exposures at the pupal stage for 2 h day-1 and 3 h day-1 over 4 days increased survival of the shock. 3. Pre-pupal exposure for 3 ..